Carrier current communication system with infrared receiver

ABSTRACT

Embodiments of a method and apparatus are described to transmit a data signal from a power supply unit, over existing direct current (DC) power transmission lines, to a residential gateway which includes an infrared (IR) receiver designed to receive optical signals. In one embodiment, the IR receiver is configured to receive a carrier current communication signal from the power supply unit over a pair of copper wires coupled to the IR receiver. The carrier current communication signals may be encoded by a transmission encoding logic circuit using pulse position modulation techniques. The received carrier current communication signals may be demodulated and decoded to reproduce an input data stream.

TECHNICAL FIELD

This disclosure relates to the field of digital data communications and,in particular, to power line communications.

BACKGROUND

Typically, telecommunication systems that provide broadband access toresidential customers contain a residential gateway which consists of anxDSL (any type of digital subscriber line generally communicated overcopper lines) modem or xPON (any type of passive optical networkgenerally communicated over optic fibers) interface combined withvarious local area networking (LAN) technologies to enable sharing thebroadband access with other computers or devices within the residence.Wireless local area network (WLAN) standards and home phone linenetworking (HPNA) are examples of such LAN technologies. In addition,some telecommunication systems may provide avoice-over-internet-protocol (VOIP) feature to allow telephone calls viathe broadband link. Some systems may, in addition to broadband accesssharing, need to distribute broadband media content such as videostreams into various locations within the residence.

Typically, the residential gateway is located inside the house. Incertain cases, however, it may be desirable to locate the residentialgateway outside the house at a network interface device (NID), such asfor example, the intelligent Network Interface Device (iNID) made by2Wire, Inc., of San Jose, Calif. An NID is the point of demarcationbetween the Unbundled Network Element (UNE) loop and the end user'sinside wire. In general, there is often no external source ofalternating current (AC) power accessible at the NID or iNID location.Consequently, powering the device from an isolated direct current (DC)power source inside the house is the generally viable option. DC powertransmission lines are used to provide power to the outside device.

A significant problem in trying to locate the residential gateway at theNID or iNID is the problem of sending communication signals between thepower supply unit (PSU) and the outside device. Conventional schemes forsending communication signals involve the installation of separate wiresbetween the outside device and the power supply unit for the purpose offacilitating communication. These schemes often require creatingadditional holes in the exterior and/or interior walls of buildings.Additional labor and material expense is associated with this additionalseparate wiring.

Other conventional schemes may try to solve the problem of requiringadditional separate wiring by making use of carrier currentcommunications. Carrier current communications systems operate byimpressing a modulated carrier signal on the existing DC powertransmission wires. In a carrier current communications system, atransmitter in the power supply unit typically modulates a carriersignal with the desired data and transmits the modulated carrier signalacross the power transmission lines. A receiver in the outside devicereceives the carrier waves and demodulates the carrier signal to extractthe data signal. The data signal may then be used by the residentialgateway as needed. One drawback of conventional carrier currentcommunications systems is that the receivers and transmitters generallyhave a complex proprietary design making them expensive to implement.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is illustrated by way of example, and not by wayof limitation, in the figures of the accompanying drawings.

FIG. 1 illustrates a block diagram of a central office containing aDigital Subscriber Loop Access Multiplexer (DSLAM) sendingcommunications across an Unbundled Network Element (UNE) loop to anintelligent Network Interface Device (iNID) according to one embodimentof the present invention.

FIG. 2 illustrates FIG. 2 illustrates a block diagram of a carriercurrent communications system including an infrared (IR) receiveraccording to one embodiment of the present invention.

FIG. 3 illustrates a block diagram of a half duplex carrier currentcommunications system including an infrared (IR) receiver according toone embodiment of the present invention.

FIG. 4 illustrates the operation of a transmission encoding logiccircuit according to one embodiment of the present invention.

FIG. 5 illustrates the operation of a decoder circuit according to oneembodiment of the present invention.

DETAILED DESCRIPTION

The following description sets forth numerous specific details such asexamples of specific systems, components, methods, and so forth, inorder to provide a good understanding of several embodiments of thepresent invention. It will be apparent to one skilled in the art,however, that at least some embodiments of the present invention may bepracticed without these specific details. In other instances, well-knowncomponents or methods are not described in detail or are presented insimple block diagram format in order to avoid unnecessarily obscuringthe present invention. Thus, the specific details set forth are merelyexemplary. Particular implementations may vary from these exemplarydetails and still be contemplated to be within the scope of the presentinvention.

The following detailed description includes several modules, which willbe described below. These modules may be implemented by hardwarecomponents, such as logic, or may be embodied in machine-executableinstructions, which may be used to cause a general-purpose orspecial-purpose processor programmed with the instructions to performthe operations described herein. Alternatively, the operations may beperformed by a combination of hardware and software.

Embodiments of a method and apparatus are described to transmit a datasignal from a power supply unit, over existing direct current (DC) powertransmission lines, to a residential gateway which includes an infrared(IR) receiver designed to receive optical signals. In one embodiment,the IR receiver is configured to receive a carrier current communicationsignal from the power supply unit over a pair of copper wires coupled tothe IR receiver. The IR receiver may be a prefabricated integratedcircuit including connection devices for a received input signal, anoutput signal, a supply voltage, a ground connection and severaladjusting or tuning devices. Generally, the functional operation of theIR receiver is that an optical signal is received at a photodetector,typically a photodiode, and converted to an electrical signal. In oneembodiment of the present invention, rather than coupling to aphotodiode, the input connection of the IR receiver is coupled to thecopper wires of the DC power transmission line through couplingcircuitry. The received electrical signal is fed into an input circuitin the receiver and to signal processing circuitry. The receiverultimately produces an output signal which is provided, for example, toa microcontroller for further processing. The IR receiver provides aninexpensive alternative to complex proprietary circuits.

FIG. 1 illustrates a block diagram of a central office containing aDigital Subscriber Loop Access Multiplexer (DSLAM) 102 sendingcommunications across an Unbundled Network Element (UNE) loop 103 to anintelligent Network Interface Device (iNID) 140, according to oneembodiment of the present invention. The DSLAM 102 sends communicationsto the iNID 140 located outside a residence 110. The iNID 140 includes aresidential gateway 106 that routes various types of communications,such as data, voice, and video, into the residence 110. The residentialgateway includes an IR receiver 143, which while normally configured toreceive optical signals, in this embodiment is configured to receivecarrier current communication signals over the DC power transmissionlines 120 and 122.

A power supply unit (PSU) 130 located inside the residence 110 couplesto a load unit via DC power transmission lines 120 and 122 to provideisolated (non-grounded DC power to the load. In this embodiment, theload unit is the iNID 140; however, in alternative embodiments the loadunit may represent one or more other devices. The PSU 130 may be locatedclose to a conventional power source such as a 120 volt alternatingcurrent (AC) outlet.

In one embodiment, the first DC power transmission line 120 is coupledto a positive terminal of the PSU 130. The second DC power transmissionline 122 is coupled to a negative terminal of the PSU 130. An isolatedDC signal is sent from the PSU 130 to the load 140 via the DC powertransmission line pair.

In certain embodiments, it may be advantageous for the PSU 130 and theload 140 to exchange communication messages with each other. Thecommunication messages may include, for example, monitoring informationfor components such as batteries or switches, control signals toactivate light emitting diodes (LEDs) or audio alarms, or reset signals.

The design for the load 140 allows power to be delivered from a powersupply unit that is located within a residence 110 to power the load 140using DC power transmission lines. The DC power transmission lines canalso be used to transmit the communication messages described abovebetween the PSU 130 and the load 140 using a carrier currentcommunication scheme. A carrier current communication scheme may operateby sending a modulated carrier signal over the DC power transmissionlines that is received by IR receiver 143 in the load 140.

FIG. 2 illustrates a block diagram of a carrier current communicationssystem including an infrared (IR) receiver according to one embodimentof the present invention. The carrier current communications systemincludes power supply unit 130 and power load unit 140 discussed abovewith respect to FIG. 1. Power supply unit 130 includes transmissionencoding logic circuit 231 and DC power supply 232. Power load unit 140includes DC power load 242, IR receiver 143 and decoder circuit 244. Itshould be understood that power supply unit 130 and power load unit 140may include additional components or modules which are omitted from thisdescription so as not to obscure the present invention.

DC power is provided by DC power supply 232 in PSU 130 to DC power load242 in power load unit 140. In one embodiment, DC power load 242 isresidential gateway 106 shown in FIG. 1. The DC power is transmitted viaDC power transmission lines 120 and 122. In one embodiment, DC powertransmission lines 120 and 122 are also used to transmit a carriercurrent communications signal from PSU 130 to power load unit 140. Adigital data stream is received at an input of transmission encodinglogic circuit 231. Transmission encoding logic circuit 231 modulates acarrier wave signal to include data from the input data stream. In oneembodiment, transmission encoding logic circuit 231 uses a pulseposition modulation technique to modulate the carrier wave. Theoperation of transmission encoding logic circuit 231 will be describedfurther below with respect to FIG. 4.

In one embodiment, transmission encoding logic circuit 231 is coupled toDC power transmission lines 120 and 122 through a transformer 251.Transformer 251 includes a first winding and a second winding. The firstwinding is coupled to an output of transmission encoding logic 231. Thesecond winding has a first end coupled to capacitor 252 and a second endcoupled to resistor 253. Capacitor 252 and resistor 253 may also becoupled to DC power transmission lines 120 and 122 respectively.Transformer 251 effectively decouples transmission encoding logiccircuit 231 from DC power supply 232. Transformer 251 prevents currentfrom DC power supply 232 from flowing into transmission encoding logiccircuit 231 and prevents the transmitter DC output current frominfluencing DC power supply 232. In one embodiment, transformer 251 hasa winding ratio of approximately 1:1 and an inductance value ofapproximately 345 microhenries (μH). Capacitor 252 serves to prevent thetransformer 251 from providing a DC burden on DC power transmissionlines 120 and 122. In one embodiment, capacitor 252 has a capacitancevalue of approximately 0.01 microfarads (μF). Resistor 253 protectstransmission encoding logic circuit 231 from a large transient voltagein DC power transmission lines 120 and 122 that may damage transmissionencoding logic circuit 231. In one embodiment, resistor 253 has aresistance value of approximately 1 kiloohm (kΩ). In alternativeembodiments, other values for transformer 251, capacitor 252 andresistor 253 may be used.

In one embodiment, inductor 254 is coupled between the output of DCpower supply 232 and DC power transmission line 120. Inductor 254 stopsthe signal imposed on DC power transmission line 120 by transmissionencoding logic circuit 231 from being dissipated by the relatively lowimpedance of DC power supply 232. Inductor 264 is similarly coupled andserves the same purpose for DC power load 242. In one embodiment,inductors 254 and 264 have an inductance value of approximately 220 μH,however, in alternative embodiments, inductors 254 and 264 have otherinductance values.

In power load unit 140, IR receiver 143 is coupled to DC powertransmission lines 120 and 122 through a transformer 265. Rather thanbeing configured to receive an optical signal, IR receiver 143 isconfigured to receive a carrier current communication signal sent viatransmission lines 120 and 122. Transformer 265 includes a first windingand a second winding. The first winding is coupled to an input of DCpower load 242 and the second winding has a first end coupled tocapacitor 266 and a second end coupled to resistor 267. Capacitor 266and resistor 267 may also be coupled to DC power transmission lines 120and 122, respectively. Transformer 265, capacitor 266 and resistor 267serve a similar purpose and may have similar values as transformer 251,capacitor 252 and resistor 253, respectively.

IR receiver 143 receives the modulated carrier current communicationsignal from DC power transmission lines 120 and 122. Additionally, IRreceiver 143 demodulates the received signal to form a binary voltagewaveform. The binary voltage waveform is received at an input of decodercircuit 244. Decoder circuit 244 decodes the waveform to reproduce thedigital data stream initially received by transmission encoding logiccircuit 231. The operation of decoder circuit 244 will be discussedfurther below with respect to FIG. 5.

FIG. 3 illustrates a block diagram of a half duplex carrier currentcommunications system including an infrared (IR) receiver according toone embodiment of the present invention. The half duplex carrier currentcommunications system includes power supply unit 130 and power load unit140 as described above with respect to FIGS. 1 and 2. In thisembodiment, both power supply unit 130 and power load unit 140 include atransmission encoding logic circuit 331, 341, a DC power supply 332 or aDC power load 342, an IR receiver 333, 143, and a decoder circuit 334,344. The half duplex implementation operates similarly to the system ofFIG. 2 except that communication is possible in both directions (i.e.,from PSU 130 to power load unit 140 or from power load unit 140 to PSU130) since both units include a transmitter and receiver.

The half duplex carrier current communications system includestransformers 251, 355, 361 and 265, capacitors 252, 356, 362 and 266,resistors 253, 357, 363 and 267, and inductors 254 and 264. Thesecomponents serve a similar purpose and may have similar values as thecorresponding components discussed above with respect to FIGS. 1 and 2.

FIG. 4 illustrates the operation of a transmission encoding logiccircuit according to one embodiment of the present invention. Theencoder functionality may be implemented in a number of ways includingin software executed by a microprocessor, in a programmable logicdevice, or in an application specific integrated circuit (ASIC). In oneembodiment, the encoder implements a pulse position modulation encodingscheme. In one embodiment, the encoder is transmission encoding logiccircuit 231 shown in FIGS. 2 and 3 or transmission encoding logiccircuit 341 shown in FIG. 3.

The encoder receives an input data stream that is stored in register402. The input data stream may be in a number of formats, including forexample, a parallel data stream or a serial data stream. The input datastream is read out of register 402 and into pause timer 404. Pause timer404 selects between two values for a pause length based on the inputdata. In one embodiment, a short pause represents a zero bit and a longpause represents a one bit. The pause timer output is sent to pausetimer edge extractor 406. Pause timer edge extractor 406 measures eachfalling edge in the pause timer output signal and creates a short pulsethat will be used trigger a burst timer pulse. The pause timer edgeextractor 406 feeds burst timer 408. Each short pulse is used to triggerthe start of a longer pulse in the burst timer output. The burst timeroutput is fed to the burst timer edge extractor 410 which measures eachfalling edge of the burst timer output and signals the pause timer wheneach pulse ends, thus signaling the start of a new pause. The bursttimer output is also fed to carrier wave modulator 412 which modulates acarrier wave received from carrier generator 414 to include the bursttimer output signal. In one embodiment, the carrier wave is a 58kilohertz (kHz) sine wave; however, in alternative embodiments anothercarrier wave may be used.

FIG. 5 illustrates the operation of a decoder circuit according to oneembodiment of the present invention. In one embodiment, the decoder maybe decoder circuit 244 shown in FIGS. 2 and 3 or decoder circuit 334shown in FIG. 3. The decoder receives a binary voltage waveform from theoutput of an IR receiver. The binary voltage waveform is received atedge extractor 502. Edge extractor 502 measures the leading edge ofevery pulse in the received waveform. Edge extractor 502 feeds timer 504which selects between two values based on the time between edge pulses.In one embodiment, a short pause represents a zero bit and a long pauserepresents a one bit. Bit extractor 506 interprets the timer output andfeeds bit register 508 with the data stream. The output of bit register508 matches the initially encoded digital data stream and may be used bythe unit encompassing the decoder as needed.

The digital processing device(s) described herein may include one ormore general-purpose processing devices such as a microprocessor orcentral processing unit, a controller, or the like. Alternatively, thedigital processing device may include one or more special-purposeprocessing devices such as a digital signal processor (DSP), anapplication specific integrated circuit (ASIC), a field programmablegate array (FPGA), or the like. In an alternative embodiment, forexample, the digital processing device may be a network processor havingmultiple processors including a core unit and multiple microengines.Additionally, the digital processing device may include any combinationof general-purpose processing device(s) and special-purpose processingdevice(s).

Although the operations of the method(s) herein are shown and describedin a particular order, the order of the operations of each method may bealtered so that certain operations may be performed in an inverse orderor so that certain operation may be performed, at least in part,concurrently with other operations. In another embodiment, instructionsor sub-operations of distinct operations may be in an intermittentand/or alternating manner.

Certain embodiments may be implemented as a computer program productthat may include instructions stored on a machine-readable medium. Theseinstructions may be used to program a general-purpose or special-purposeprocessor to perform the described operations. A machine-readable mediumincludes any mechanism for storing or transmitting information in a form(e.g., software, processing application) readable by a machine (e.g., acomputer). The machine-readable medium may include, but is not limitedto, magnetic storage medium (e.g., floppy diskette); optical storagemedium (e.g., CD-ROM); magneto-optical storage medium; read-only memory(ROM); random-access memory (RAM); erasable programmable memory (e.g.,EPROM and EEPROM); flash memory; electrical, optical, acoustical, orother form of propagated signal (e.g., carrier waves, infrared signals,digital signals, etc.); or another type of medium suitable for storingelectronic instructions.

Additionally, some embodiments may be practiced in distributed computingenvironments where the machine-readable medium is stored on and/orexecuted by more than one computer system. In addition, the informationtransferred between computer systems may either be pulled or pushedacross the communication medium connecting the computer systems.

In the foregoing specification, the invention has been described withreference to specific exemplary embodiments thereof. It will, however,be evident that various modifications and changes may be made theretowithout departing from the broader scope of the invention as set forthin the appended claims. The specification and drawings are, accordingly,to be regarded in an illustrative sense rather than a restrictive sense.

What is claimed is:
 1. An apparatus comprising: a power supply unit; apower load unit coupled to the power supply unit through a directcurrent (DC) power transmission line pair; and means for receiving acarrier current communication signal, sent from the power supply unitover the DC power transmission line pair, at an infrared (IR) receiverin the power load unit, wherein the IR receiver is designed to receiveoptical signals.
 2. The apparatus of claim 1, wherein the means forreceiving comprises: a first transformer having a first winding and asecond winding, wherein the first winding is coupled to an input port ofthe IR receiver; a first capacitor coupled to a first end of the secondwinding of the first transformer; and a first resistor coupled to asecond end of the second winding of the first transformer.
 3. A methodcomprising: transmitting a carrier current communication signal from apower supply unit via a direct current (DC) power transmission linepair; and receiving the carrier current communication signal at aninfrared (IR) receiver in a power load unit, wherein the IR receiver iscoupled to the DC power transmission line pair.
 4. The method of claim3, further comprising: receiving an input data stream at a transmissionencoding logic circuit in the power supply unit and modulating a carrierwave signal to include data from the input data stream using a pulseposition modulation technique.
 5. The method of claim 4, whereinreceiving the carrier current communication signal comprises receivingthe modulated carrier wave signal at the IR receiver.
 6. The method ofclaim 5, further comprising: demodulating the received modulated carrierwave signal to form a binary voltage waveform.
 7. The method of claim 6,further comprising: decoding the binary voltage waveform to reproducethe input data stream.
 8. A carrier current communications system,comprising: a power supply unit: a power load unit coupled to the powersupply unit through a direct current (DC) power transmission line pair,wherein the power load unit comprises an infrared (IR) receiver coupledto the DC power transmission line pair and configured to receive carriercurrent communication signals.
 9. The carrier current communicationssystem of claim 8, wherein the power load unit comprises: a firsttransformer having a first winding and a second winding, wherein thefirst winding is coupled to an input port of the IR receiver; a firstcapacitor coupled to a first end of the second winding of the firsttransformer; and a first resistor coupled to a second end of the secondwinding of the first transformer.
 10. The carrier current communicationssystem of claim 9, wherein the DC power transmission line pair comprisesa first DC power transmission line coupled to the first capacitor and asecond DC power transmission line coupled to the first resistor.
 11. Thecarrier current communications system of claim 10, wherein the powerload unit further comprises: a decoder circuit having an input coupledto an output of the IR receiver.
 12. The carrier current communicationssystem of claim 11, wherein the power supply unit comprises atransmission encoding logic circuit coupled to the DC power transmissionline pair.
 13. The carrier current communications system of claim 12,wherein the power supply unit further comprises: a second transformerhaving a first winding and a second winding, wherein the first windingis coupled to an output port of the transmission encoding logic circuit;a second capacitor coupled to a first end of the second winding of thesecond transformer; and a second resistor coupled to a second end of thesecond winding of the second transformer.
 14. The carrier currentcommunications system of claim 13, wherein the second capacitor iscoupled to the first DC power transmission line and the second resistoris coupled to the second DC power transmission line.
 15. The carriercurrent communications system of claim 12, wherein the transmissionencoding logic circuit is configured to modulate a carrier wave signalto include data from a received input data stream using a pulse positionmodulation technique.
 16. The carrier current communications system ofclaim 12, wherein the power supply unit further comprises: a DC powersupply coupled to the DC power transmission line pair.
 17. The carriercurrent communications system of claim 16, wherein the power supply unitfurther comprises: a first inductor coupled between the DC power supplyand the first DC power transmission line.
 18. The carrier currentcommunications system of claim 11, wherein the power load unit furthercomprises: a DC power load coupled to the DC power transmission linepair.
 19. The carrier current communications system of claim 18, whereinthe power load unit further comprises: a second inductor coupled betweenthe DC power load and the first DC power transmission line.
 20. Thecarrier current communications system of claim 19 wherein the power loadunit further comprises: a second transmission encoding logic circuit; athird transformer having a first winding and a second winding, whereinthe first winding is coupled to an output port of the secondtransmission encoding logic circuit; a third capacitor coupled to afirst end of the second winding of the third transformer; and a thirdresistor coupled to a second end of the second winding of the thirdtransformer.
 21. The carrier current communications system of claim 20,wherein the power supply unit further comprises: a second IR receiver; asecond decoder coupled to an output of the second IR receiver; a fourthtransformer having a first winding and a second winding, wherein thefirst winding is coupled to an input port of the second IR receiver; afourth capacitor coupled to a first end of the second winding of thefourth transformer; and a fourth resistor coupled to a second end of thesecond winding of the fourth transformer.